<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .parent {
            width: 100px;
            height: 100px;
            display: flex;
            align-items: center;
            justify-content: center;
            background: skyblue;

            &:hover {
                background: blanchedalmond;
            }

            .child {
                width: 60px;
                height: 60px;
                background: yellowgreen;
            }
        }
    </style>
</head>

<body>
    <div class="parent">
        <div class="child"></div>
    </div>
</body>

</html>